Switch



Patented Sept. 19, 1950 SWITCH Gordon S. Loy, Belmont, Mass., assignorto Westinghouse Electric Corporation, East Pittsburgh, Pa., acorporation of Pennsylvania Application October 30, 1946, Serial No.706,737

6 Claims.

This invention relates generally to electric control switches, and morespecifically to such switches adapted to be operated by housing doors.

Where electrical apparatus is mounted in an enclosure it is generallydesirable to provide a control switch for the apparatus to be operatedby the door for the enclosure so that the switch will be closed toenergize the apparatus when the door is closed, and will open tode-energize the apparatus when the door is opened. While such anarrangement is satisfactory from a safety standpoint, there areoccasions when it is necessary to have the apparatus energized when thedoor for the enclosure is not closed, as during certain repair and testoperations, or for emergency operation in cases where the door may bedamaged or destroyed entirely.

Accordingly, one object of this invention is to provide in adoor-operated type of electric switch adapted to be closed when the dooris closed and open when the door is open, novel means for selectivelyclosing the switch when the door is open.

Another object of this invention is to provide in a door-operated typeof electric switch adapted to be closed when the door is closed and openwhen the door is open, novel means for manually closing the switch whenthe door is open, and for automatically resetting the switch foroperation by the door in response to closing of the door.

A more general object of this invention is to provide in a switch whichis biased to one operative position and is provided with a reciprocableoperating member, novel means for selectively retaining the operatingmember at its position corresponding to the other operative position ofthe switch.

Another object of this invention is to provide in a switch which isbiased to one operative position and is provided with a reciprocableoperating member, novel means for selectively retaining the operatingmember at its position corresponding to the other operative position ofthe switch, and operative automatically in response to operatin movementof said member to release the retaining means.

Another object of this invention is to provide in connection withelectrical apparatus mounted in a housing, a novel control switch forthe apparatus adapted to be closed by closing of the housing door andopened when the door is opened, and yet being capable of manualadjustment to be retained at closed position when the door is open andto be automatically released on a subsequent closing of the door,

Still another object of this invention is to provide a novel attachmentfor a standard type of switch, whichattachment includes operating andlatch means for the switch.

These and other objects of this invention will become more apparent uponconsideration of the following description of a preferred embodimentthereof, when taken in connection with the attached drawing, in which:

Figure 1 is a front view of a housing for elec-. trical apparatusembodying a control switch constructed in accordance with thisinvention;

Fig. 2 is a partial sectional view of the housing shown in Fig.1, withthe housin door shown in dot-dash lines at a partially open position;

Fig. 3 is a side view of the switch structure employed with the housingof Figs. 1 and 2; and

Fig. 4 is a longitudinal section view of the switch shown in Fig. 3.

The housing 2 shown in Figs. 1 and 2 may comprise side walls 4, a topwall 6, and a front wall 8 defining an opening for a door Ill. Thehousing may also include a rear wall (not shown) The door II] ispreferably hinged on one side as by hinges i4, and has an operating knobl2 or the like at the opposite side thereof, to facilitate openin andclosing of the door.

Any desired electrical apparatus [6 may be mounted within housing 2, andin order to supply electrical energy to such apparatus, supplyconductors I8 and 29 are provided with the former being directlyconnected with apparatus l6, and the latter being connected withapparatus l6 through a control switch 22. The control switch 22 isillustrated as being secured to the inner side at the top of front wall8 of the housing, as by bolts or rivets 24, in a position such that theoperating member of the switch is adapted to be engaged by door Inadjacent to the closed position of the door so as to be opened andclosed by the door.

Control switch 22 preferably employs a standard design of switch unit 26of the type having separable contacts, one of which is spring biased outof engagement with the other, and having an actuating plunger which maybe depressed to close the contacts, and having some overtravel in thecircuit closing direction. Such a switch is illustrated in Figs. 3 and 4as comprising a generally tubular base 28 of insulating materialpreferably a molded insulating material, having contact strips 30inserted in one end of base 28 in opposed relation, with each striphaving a laterally extending contact portion 32 adapted to extendtowards each other, and to engage an internal shoulder 34 formedintegrally with base 28. The contact strips are held in base 28 by asubstantially cup-shaped plug 36 which is inserted in the base betweenthe contact strips and is secured therein together with the contactstrips 30, by opposed screws 38 extending through apertures in theopposite sides of base 28 and through contact strips 36 to be threadedlyengaged in opposite sides of plug 36.

The opposite end 40 of base 28 is interiorly threaded for threadedlyreceiving one end of a guide tube 42. An operating plunger 44 isprovided with an enlarged base portion 46 adapted to relatively closelyslidably fit within guide tube 42 and to be normally held in engagementwith a shoulder 48 provided at the outer end of guide tube 42, by a coilcompression spring 50 reacting between plunger base 46 and shoulder 34in base 28. Within guide tube 42, plunger 44 is provided with a contactcarrying rod 52, preferably threaded into base 46 of the plunger, andprovided with a head 54 at its inner end, on which a bridging contactdisk 56 is adapted to be held by a coil compression spring'58 reactingbetween contact disk 56 and plunger base 46.

It is apparent from the foregoing that the switch unit 26 will operatesubstantially in the manner previously described, that is, the circuitthrough the switch is normally held open by compression spring 50, whichalso serves to maintain plunger 44 at an outer position. When it isdesired to close the circuit through the switch, plunger 44 is movedinwardly relative to the switch and the, circuit is closed when bridgingcontact disk 56 engages contact parts 32 of the conducting strips 30. Itwill be noted that plunger 44 may be moved beyond the point wherebridging contact disk 56 engages contact parts 32 because contact disk56 is slidable on rod 52, and the disk will be held in engagement withcontact parts 32 by compression spring 58, and the plunger may have,therefore, over-travel relative to bridging contact disk 56 until thehead 54 thereof engages the outer end or plug 36. Obviously, as soon asplunger 44 is released, compression spring 50 Will operate'to restorethe plunger to its extended position shown in the drawing.

In accordance ard type switch as the switch unit 26 is adapted to beprovided with an operating and control unit which is operable toretainthe switch actuating plunger at a closed circuit position, and isadaptedto be automatically released from such a powith this invention,such a standsition-during over-travel of the operating plunger relativeto the'bridging contact. For this purpose, a guide tube 60 is internallythreaded at one end, so as to be threaded onto the outer end of guidetube 42 and be secured in adjusted position thereon by a lock nut 62. 'Aplunger 64 is adapted to be slidably mounted in the outer end of guidetube 60 and hasa reduced outer end portion366', adapted to be actuatedby a door, such as the door 10 of housing 2, or the like. The outerend66 of the plunger may be provided with a transversely extending slot 68,for a purpose to be described. Plunger 64 is provided adjacent its innerend with a transverse pin 10 secured therein and adapted to projecttherefrom into an elongated slot 12 provided in guide tube 60. Slot [2extends longitudinally in the direction of sliding movement of theoperating plunger, and opens at one side intoa locking recess 14 whichextends at an inclination relative to the extent of slot 12; Inorder tomount the switch device illustrated'in the drawing, a mounting bracket16 is provided with a relatively large threaded opening adapted to bethreaded on the outer end of guide tube 68, and to be secured inadjusted position thereon by a lock nut 80. Mounting bracket 16 is alsoprovided with mounting apertures 18 for receiving the mounting bolts 24.

It will now be apparent that with the switch structure in its normalopen circuit position illustrated in Fig. 4, the circuit may be closedby pushing plunger 64 to the right to thereby push plunger 44 to theright and close the circuit through the switch unit in the mannerdescribed above. Similarly, when the motive force is removed fromplunger 64, the switch will automatically be opened by compressionspring 50 and the parts restored to the positions illustrated. However,if it is desired to maintain the switch closed without the necessity ofcontinuously exerting a force on plunger 64, the plunger may be pushedto the right until the closed circuit position is reached, whereupon pin18 on plunger 64 will be opposite locking recess 14 in guide tube 60, sothat by rotating plunger 64 in a clockwise direction pin 10 will bemoved into locking recess 14 to prevent outward movement of the plungerand bridging contact 56 of the switch, and thereby maintain the switchat a closed circuit position. The transverse slot 68 in the outer end ofplunger 64 permits the use of a screw driver, or the like, for rotatingthe plunger in the manner described above. or course, when it is desiredto open the switch after it has been locked closed in the mannerdescribed above, plunger 64 may be manually rotated counterclockwise,but this is not necessary in view of the inclined relation of lockingrecess 14 with respect to slot 12, because it is apparent that if aforce is exerted on plunger 64 tending to move it further inwardly sothat it will over-travel with respect to bridging contact disk 56, pin18 will be cammed out of locking recess 14 back into slot 12, so thatwhen such force on the plunger is released, compression spring 50 willbe free to move the plunger and bridging contact of the switch to theopen circuit position illustrated.

The special utility of the switch structure described above, renderingits special adaption for operation by a housing door will now beapparent, because when such a switch assembly is mounted as shown inFigs. 1 and 2 so that the outer end 66 of plunger 64 is positioned to beengaged by the housing door just prior to complete closing of the door(Fig. 2), so that the plunger will be moved inwardly upon final closingmovement of the door, the switch will be closed by the door when thelatter is fully closed, and opened only when the door is opened. In caseelectrical apparatus I6 mounted within the housing is supplied with highvoltage, this switch arrangement provides that the apparatus isenergized only when the door is closed, so that it is impossible foranyone to open the door and accidentally come into contact with anyparts within the 16 with the housing door open has passed, it isnecessary that the switch be restored to its normal operation, that is,to be opened and closed by opening and closing of the door. It will beapparent that with the particular arrangement described above it will beimpossible for an operator to neglect this feature as might be possiblein the case of a switch latch requiring a separate manual operation torelease it, because upon a subsequent closing of the door, plunger 64 isautomatically released by movement of pin out of locking recess H and isthus automatically moved to its normal position where it will open upona later opening of the door and will be closed when the door is closed.

From the foregoing, it is apparent that the structure disclosed hereinprovides a novel switch arrangement employing a switch having contactsand an operating member normally biased to one position, and adapted tobe operated against the bias to its other position, together with meansselectively operable to hold the switch at such other position againstits bias, and means for automatically releasing the switch from suchholding means upon predetermined normal operation of the switch.Furthermore, it will be apparent that the switch structure described isespecially adapted for operation by a housing door, or the like,especially where the switch acts to control the supply of electricalenergy to apparatus mounted within the casing, where it may be desirableto have the switch held at its position corresponding to that occupiedwhen the housing door is closed, even when the door is open. Moreover,the switch structure described is adapted for use with a standard typeof switch unit of the general type described.

Having described a preferred embodiment of the invention in accordancewith the patent statutes, it is desired that this invention be notlimited to this particular embodiment inasmuch as it will be apparent,especially to those skilled in the art, that many changes andmodifications may be made in this particular structure without departingfrom the broad spirit and scope of the invention. Accordingly, it isdesired that this invention be interpreted as broadly as possible, andthat it be limited only as required by the prior art.

I claim as my invention:

1. In a switch, separable contact means, a reciprocable operating memberfor actuating one of said contact means to open and closed circuitpositions, said one contact means and operating member being biased formovement in one direction to one position of said separable contactmeans, said operating member and movable contact means being normallyfree to move to said other position upon application of operating forceto said operating member sufficient to overcome said bias and being freeto return to said one position under the influence of said bias uponremoval of said operating force, means providing for over-travel of saidoperating member with respect to said contact means in the oppositedirection beyond the other operative position of said separable contactmeans, means responsive to movement of said member in another directionwhen at a position corresponding to said other contact position forholding said member at said position against movement by said bias, andcam means cooperating with a part of said member during over-travelthereof for releasing said holding means by moving said operating memberin a direction opposite said other direction to restore said member forreciprocal movement.

2. In a switch, separable contact means, a reciprocable operating memberfor actuating one of said contact means to open and closed circuitpositions, said one contact means and operating member being biased formovement in one direction to one position of said separable contactmeans, means providing for over-travel of said operating member withrespect to said contact means in the opposite direction beyond the otheroperative position of said separable contact means, locking projectionand recess means one of which is movable with said member and the otherof which is fixedly mounted, said projection and recess means beingnormally out of engagement during reciprocation of said member butarranged so that said projection means will engage one side of saidrecess means when said member is rotated in one direction at a positionthereof corresponding to said other contact position for holding saidmember at said position against said bias, and the other side of saidrecess means being inclined with respect to the direction of reciprocalmovement to positively rotate said member back to normal position inresponse to over-travel of said member.

3. In a switch, separable contact means, a reciprocable operating memberfor actuating one of said contact means to open and closed circuitpositions, said one contact means and operating member being biased formovement in one direction to one position of said separable contactmeans, means providing for over-travel of said operating member withrespect to said contact means in the opposite direction beyond the otheroperative position of said separable contact means, a tubular guide forsaid member, a projection on said member normally received in anelongated opening in said guide during reciprocable movement of saidmember, said opening having side edges substantially parallel with thedirection of movement of said operating member and movable contactmeans, and one side edge of said opening having an angularly extendingrecess therein positioned to receive said projection upon rotation ofsaid member when at a position thereof corresponding to said othercontact position for holding said member at said position against saidbias, and the side of said recess means engaging said projection duringover-travel of said member being cam-shaped to cause rotation of saidmember back to normal position.

4. In switching apparatus having a switch of the type comprisingseparable contacts biased apart and a contact operating plunger slidablein a guide tube, the combination of a separate operating unit having asecond operating plunger slidably mounted in a second guide tube, meanssecuring said tubes together in axially aligned relation to secure saidunit in operative relation to said switch, and said second tube andoperating plunger having interfitting recess and projection meansarranged to retain said second plunger at one position against said biasin response to rotation thereof and to release said second plunger inresponse to predetermined sliding movement thereof.

5. In switching apparatus having a switch of the type comprisingseparable contacts biased apart and a contact operating plunger slidablein a guide tube, the combination of a separate operating unit having asecond operating plunger slidably mounted in a second guide tube, meanssecuring said tubes together in axially aligned relation to secure saidunit in operative relation to said switch, a longitudinally extendingslot in said second tube receiving a pin on said second plunger forguiding and limiting reciprocating movement of said second plunger insaid second tube, and a recess in one side edge of said slot forreceiving said pin when said second plunger is rotated at its closedcircuit position to hold said contacts closed against said bias.

6. A switch comprising, separable contact means, a reciprooableoperating member for actuating one of said contact means to open andclosed circuit positions, said one contact means and operating memberbeing biased for movement in a direction away from the other of saidcontact means to an open circuit position, said operating member'andmovable contact means being normally free to move to closed circuitposition upon application of operating force to said member suflicientto overcome said bias and being free to return to open circuit positionunder the influence of said bias upon removal of said operating force,means providing for over-travel of said operating member with respect tosaid contact means in the circuit closing direction and beyond theposition it occupies when said contact means are first engaged, meansresponsive to movement of said member in another direction when at aposition where said contact means are in engagement for holding saidmember at such position against movement by said bias, and cam meanscooperating with a part of said member during over-travel thereof forreleasing said holding means for reciprocal movement by moving saidoperating member in a direction opposite said other direction.

GORDON S. LEY.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,309,840 Bramming July 15, 19191,394,398 Benjamin Oct. 18, 1921 2,132,428 Meuer Oct. 1'1, 19382,156,443 Zook May 2, 1939 2,303,516 Von Mehren Dec. 1. 1942 2,389,259Horlacher Nov. 20, 1945.

